[daveinfl]

Thanks for the comments so far. Bill ... two of the three vents I replaced. I don't see cracks around them. But you never know. I'm glad you haven't had the leak problem. It can be a pain and you worry and watch every time it rains.

Wingedryder - The DICOR product that I was going to use was for aluminum. I saw the product you were talking about. But I was afraid it would not work. I do have one more idea that I may try ... if I can find the product.

Back in the 80's I customized a van myself. I put roof vents in and didn't have any trouble with them. But one thing I did was put a product as a last step that was almost like a self leveling rubber. It was gray in color and went on with a heavy paint brush. I ran this stuff up just barely under the vent and painted it out about 2" all the way around the vent opening. If I can find what it was, I might give it a try before I go to the expense of taking it in for a new roof. To me it almost worked like a flashing around a chimney.

Hopefully this thread will generate some more ideas as I know this is a problem for many in the forum.

Thanks again everyone!